Some time this summer, a piledriver should break ground outside Euston station in London. It will mark the start of the most extravagant infrastructure project in Britain’s history: High Speed 2, a railway line running 335 miles from London to Birmingham, Manchester, Sheffield and Leeds. The line is budgeted at £55bn, although late last year its cost was widely reported to be closer to £70bn.

The bill that will enable construction to begin passed through the House of Commons in March and is currently before the House of Lords. It is 444 pages long, with a gargantuan accompanying environmental report of 50,000 pages. Yet in the six years since HS2 was formally proposed, countless alarms have been raised about the project’s spiralling costs and diminishing benefits. Its fervent supporters have wheeled out increasingly tenuous justifications for its construction, but the zombie train refuses to die. Indeed, as the claims for its necessity have become weaker and weaker, its backers only become more adamant that it is a matter of supreme national importance that the project goes ahead.

The story of HS2 is a story of our persistent failure to properly plan and prioritise major infrastructure projects. Politicians and civil servants find it hard to reverse poor decisions, even when their initial rationale has slipped into distant memory. With its mix of political machismo, muddled planning, and boundless expense, HS2 should be a cautionary tale for the other megaprojects waiting in the wings: Hinkley Point power station (£20bn), a third runway at Heathrow (£18bn) and London’s Crossrail Two (£32bn).

The project itself goes back to 1982, when a group of managers from the nationalised British Rail visited the new TGV railway in France. They returned boggle-eyed at the sight of a train racing at 270kmph (150mph) down its own track, crossing France, from Paris to Lyon, in two hours. Among the visitors was a 35-year-old civil engineer, Jim Steer. He was captivated by speed and, as he told me recently, dismayed by the conviction of his colleagues that “in Britain we would never be allowed to do it”. As with Concorde, Steer understood that the idea of speed could arouse politicians and open purse strings to projects that might otherwise get nowhere. It was speed that had persuaded such prestige-sensitive governments as Japan and France to build new railways.

Steer was to be one of three men – the others were a rail-obsessed peer and a chancellor of the exchequer – who kept the dream of high-speed rail alive over the next three decades. Educated at Imperial College London, he trained at the contractors Freeman Fox, but in 1978 he turned freelance as a transport consultant, setting up his own firm: Steer Davies Gleave. A natural buccaneer, he proved adept at winning consultancy contracts anywhere there was a glimmer of interest in fast trains. “Jim was like a terrier,” a contemporary told me. “His name popped up at the foot of reports, inquiries and surveys, wherever the words high-speed rail occurred.”

Britain’s trains in the 1980s were in a state of decline. Margaret Thatcher disliked them and found the public’s affection for them baffling. She omitted British Rail from her privatisation programme. “The British public won’t stand for privatising the trains or the Royal Mail,” she once confided to me. It was only the arrival of John Major as prime minister in 1990 that brought the issue to the fore. Despite their respective images, he was a far more determined privatiser than her. But his chosen form of privatisation – with a private company, Railtrack, owning the infrastructure, and separate companies to run the trains – proved financially unstable. It crippled rail investment and leadership throughout the 1990s.

For men like Steer, the one ray of hope shone from across the English Channel. The Channel tunnel, begun in 1987 from Dover to Calais, he says, was “the best thing that could have happened to us”. New high-speed trains would connect Britain’s passenger rail network with the rest of Europe. British Rail duly began to plan a dedicated high-speed pathway through Kent and south London to a sub-surface terminal at King’s Cross.

This route was sabotaged in 1991 for blatantly political reasons: the deputy prime minister, Michael Heseltine, directed that the route be changed to enter London through the Thames estuary to the east, rather than from the south, in order to aid his plans for the regeneration of east London. This delayed the start of construction, so that when the Channel tunnel opened for business in 1994, the first passenger trains to run through it were brought by Eurostar along busy commuter lines into Waterloo, at barely two-thirds the speed they travelled across the plains of Picardy. It was a humiliating demonstration of the state of Britain’s railways.

In 1996, the government finally set up a new company, London and Continental Railways (LCR), to begin construction of the new eastern pathway. This passed under the Thames estuary and through Essex into St Pancras station. It doubled the cost of the planned track. Within two years, LCR was in financial difficulties and had to be bailed out by the government.

Not a mile of this new track was laid when Tony Blair’s Labour government took office in 1997, eager to make a breakthrough in transport. John Prescott, who held the transport portfolio as deputy prime minister, did not reverse rail privatisation. Instead he set up the Strategic Rail Authority (SRA), which was meant to coordinate the various components of the privatised rail network, run by the former boss of the Channel tunnel, Sir Alastair Morton. The SRA was soon feuding with the rail regulator and the train operators, while Railtrack collapsed into liquidation andeffective renationalisation as Network Rail.

But the SRA was a godsend for Jim Steer and his dreams of speed. Its focus was not running trains but the future of railways, and in 2002 he secured the post of director of strategy. The SRA had already commissioned the consultancy firm Atkins to consider options for “new rail capacity” on inter-city routes north out of London. They suggested not one route but two, through the East and the West Midlands, each priced at £30bn. These sums were huge. Steer recalled glumly: “I could see such a project was never high in Morton’s priority list.”

The SRA was soon abolished, and Steer returned to consultancy. In 2006, he set up a lobbying group, Greengauge 21, to promote high-speed rail. The group produced a stream of reports, held seminars, briefed MPs and sought support among local councils in the north – anyone who might welcome a fast link to London.

Like similar lobbies for airlines, roads and defence, Greengauge 21 found ready backers in private industry eager for government contracts. Steer had the advantage of a specific project, a new railway to the north, and a soft target in a Blair government that, in 2006, was flush with cash and eager for acceptable infrastructure. “There were not many high-profile projects around,” Steer told me. “Roads and power stations were out of fashion. They were just not being built. But rail was OK.”

Steer’s lobbying achievement was to move the idea of high-speed rail from a back shelf in Whitehall to a gleam in the eye of rail contractors. But in doing so he attracted opponents. Alistair Darling, who had become transport secretary in 2002, was opposed to diverting large sums to new infrastructure projects – and he commissioned a no-nonsense report on the role of transport in the British economy from Sir Rod Eddington, the former boss of British Airways.

Eddington’s report, which was published in 2006, was emphatic: Britain’s transport network was basically sound. The problem, he said, was congestion, especially on the roads. As far as trains were concerned, there was a need for more capacity – but this was largely on overcrowded commuter lines around big cities such as London, Bristol and Manchester. Otherwise, upgraded track, longer trains and aggressive pricing should be used to spread rail demand and constrain congestion.

As if taking aim at Steer’s lobby, Eddington added that the “ambitions and dreams of extensive new networks – that will only ever make marginal improvements to connectivity in the UK – are not a priority”. Transport policy, he said, “needs to avoid wasting time and money pursuing alluring new super high-speed motorway or rail networks or pursuing grands projets with speculative returns”.

Eddington explicitly warned against the use of crude capacity forecasts to lobby for new investment. Such projects – he presciently suggested – might prove “difficult and unpopular to stop, even where the benefit-cost equation does not stack up”. He also challenged the cult of speedfor its own sake, pointing out that above 150mph, energy use soared and rates of return plummeted. Darling enthusiastically welcomed Eddington’s report, as did his transport officials in Whitehall.

In November 2007, the much-delayed new line from the Channel tunnel – now rebranded as High Speed 1 – finally reached London. The old route into Waterloo was closed and a grand ceremony took place under the great Victorian train shed at St Pancras. Before assembled guests bathed in strobe lights and dry ice, the new trains slid into the platforms, greeted by the actor Timothy West – dressed as the Victorian engineer William Barlow, the designer of St Pancras – and by Katherine Jenkins, singing the Beatles’ Ticket to Ride. The Royal Philharmonic Orchestra played Walton’s Crown Imperial and the Queen declared: “People across the whole of Britain, not just the south-east, are suddenly quite a bit closer to Europe.”

The new route into St Pancras had taken 13 years to complete since the opening of the Channel tunnel. It had cost £5.8bn, almost three times the price of the original estimate – and cut only 40 minutes from the journey time to Paris. As for the line’s Anglo-French operator, Eurostar, in its first 10 years of operation, it won barely half its pre-opening predicted passenger numbers. This showed how wildly unreliable transport forecasts are.

That year, Gordon Brown succeeded Blair in Downing Street, and Darling moved to the Treasury, where he was soon submerged by the credit crunch and looming recession. HS1 had finally made it to London, but HS2 looked like a distant dream.

A year later, Brown made what seemed an eccentric appointment. He moved an unobtrusive but ennobled journalist, Andrew Adonis, from a junior post at education to one at transport. Five months later, he made him a full secretary of state. Lord Adonis, who had run the No 10 policy unit under Blair, had never been elected to parliament and was considered more a back-room thinktanker than a practising politician. The move to transport was at his own request, and he recalls Brown’s reaction: “He said he had never known anyone actually ask for the transport job before.” He was to be secretary of state for just 11 months. In that time he moved mountains.

Adonis, who was 45 when he moved to transport, had a boyish enthusiasm for projects. He had ardently promoted academy schools under Blair; he would later try to forge an unsuccessful Labour-Liberal Democrat coalition package after the 2010 election. Friends regarded him as in need of a cause to which he could devote his total attention. It helped that, as a peer, he had no political hinterland nor any worry over a parliamentary career. He could concentrate exclusively on the task at hand.

Adonis leapt on high-speed rail. He admits he was “much taken by Steer”, while Steer recalls that he was impressed that Adonis “had actually read all the papers”. Like Steer, Adonis could see that speed was something that could be sold to politicians, in a way that other forms of rail investment might not. Playing on Brown’s perceived lack of patriotic fervour, Adonis stressed a constant theme: high-speed rail was in a great Victorian tradition, and France, Japan and Spain were forging ahead as Britain lagged behind. He told Brown: “I really want to do high-speed rail. Every western country has done it.” It became a matter of national pride.

Andrew Adonis when he was secretary of state for transport in 2009. Photograph: Christian Sinibaldi

At the time, Brown was politically embattled and clearly much taken by the bouncy conviction of his single-minded transport secretary. He was disinclined to argue and gave the project his blessing.

At the start of 2009, when Adonis was still a junior minister, he knew he had just over a year before an inevitable general election. “I had to honour Eddington,” he told me, “but the issue had to be not profitability but long-term economic return. Above all, we had to concentrate on how soon the railway would run out of space.” Forecasts from Network Rail were that the main railway running up the centre of Britain, from London to Birmingham and Manchester, would reach capacity in 2024. Adonis says: “The moral I drew was that the first phase of HS2 to Birmingham made sense.” After that, he felt it did not. In this, he disagreed strongly with other advocates of HS2.

Neither Steer nor Adonis worried about Eddington’s warning that commuter networks – rather than inter-city trains – were the railways most congested and most critically in need of improvement. Nor were they deflected by the fact that the existing service from London to Manchester was not exceptionally busy: various estimates over the next decade showed it at 60% to 70% of peak capacity. Commuter routes into west and south London were nearer 100%. But as Adonis’s successor as transport secretary, Patrick McLoughlin, would later admit, the money being spent on HS2 would not have otherwise gone to less grandiose rail improvement schemes. “Let’s be honest,” McLoughlin told the Sunday Times in 2013, “if we didn’t build HS2 I don’t think [George Osborne] would be saying to me, ‘Oh well Patrick, here’s the £42bn you were going to spend on HS2 to spend on other transport projects over the next 15 years.’ That’s for the fairies.” It was a virtual admission that the enormous cost was not money for the railways as such, but little more than a vanity project. When it came to infrastructure, the question for Osborne, said another observer, was: “Could it be visible from outer space?”

It was a stroke of good fortune for Adonis that the Tories would soon find their own esoteric reasons for backing high-speed rail. The same month that Adonis went to transport, in October 2008, his Tory shadow minister, Theresa Villiers, told her party conference that a future Conservative government would not build a third runway at Heathrow. She added, almost as an afterthought, it would instead “build a high-speed railway to Heathrow from Birmingham, Manchester and Leeds”. It would enter London at St Pancras and continue underground to Heathrow, a somewhat circuitous route. Steer confessed that he was taken by surprise. “But then,” he told me, “I never cease to be amazed by politicians.”

The reason for this sudden declaration by Villiers was that her leader, David Cameron, had a problem typically of his own making. In a bid to win support in marginal seats in west London, he had promised residents there that he was against any new runway at Heathrow. Labour was “pigheadedly” pursuing its plan to build one, he said. When the airport protested that this would mean curbing domestic flights from the north, Cameron responded by offering the sop of a new railway line from the north into Heathrow.

George Osborne and Andrew Adonis at the National Railway Museum in York, in 2015. Photograph: Andrew Yates / Reuters/Reuters

In the year before the 2010 general election, Adonis operated as virtually a free wheel within Brown’s crippled government. With the barest commitment from Downing Street – and none from Darling at the Treasury – he set up a private company, HS2 Ltd, ostensibly to “investigate options”. It was private, Adonis told me, “to make it seem more acceptable to the Tories”, but it had access to public funds, with a budget of £25m for its first full year of existence.

Adonis appointed the former transport department boss, Sir David Rowlands, as chairman of the company, and told him to examine “every aspect of HS2 with an open mind and to assess other options”. Adonis insists that he was still open-minded on how to meet future rail capacity on the routes north. Rowlands appeared to show no such doubts: he told interviewers that the line would be high-speed and “future-proof”, meaning that it would be designed to cope with speeds of up to 400kmph (250mph), even though no train went, or was planned to go, that fast. When Rowlands reconsidered the alternative options, he concluded that the cost of upgrading the existing track between London and Birmingham would cost £9bn – whereas the construction of an entirely new high-speed route was then estimated at only £12bn. Upgrading would yield a mere 25% increase in capacity. HS2 looked like a better deal.

Setting up HS2 Ltd was Adonis’s masterstroke. It gave the project a focus, leadership and “parastatal” presence outside Whitehall, smartly located in the former SRA offices in Victoria. As the election approached at the turn of 2010, Adonis was frantic to announce the HS2 project before he expected to lose office in May. He needed an HS2 white paper at the very least.

He also needed to nail Villiers down on her pledge. Following her unexpected declaration of support for a high-speed rail line to Heathrow, Villiers called in two former executives, John Prideaux and Chris Stokes, for advice. Prideaux was a railway professional who had profited from privatisation by shrewdly investing in British Rail’s old rolling stock, leased to the new operating companies. He and Stokes were unimpressed by Villiers’ team, who seemed to have done little homework. They later became public opponents of HS2.

Prideaux, who had run British Rail’s inter-city services in the 1980s, pointed out that first-class trains running north from Euston were well below capacity and, in the event of competition, existing operators such as Virgin would instantly undercut the premium fares charged by HS2. As for Villiers’ idea of a high-speed train from Manchester to Heathrow, Prideaux and Stokes were incredulous. “We said it was rubbish,” Prideaux recalled. “We doubted there would be half a dozen passengers getting off at Heathrow from each train, and they would need another train to get to a terminal.” Stokes concluded that “for the Tories, HS2 was really about Heathrow runways … as if the train was an afterthought.”

When Adonis heard that Prideaux was advising Villiers, he was delighted. He told his officials and HS2 Ltd to “give them all the help they need, short of removing official papers from the office”. Adonis, a Labour minister, was in effect aiding the Tory opposition to lobby against his own Treasury.

One thing Adonis understood was that the announcement of a preferred line of route would be a sure indicator that HS2 was serious. It would make the project seem real. It would also narrow the arc of uncertainty, and therefore potential protest, from constituencies across the Midlands. Too much noise from too many of them might cause Cameron to abandon the project.

HS2 Ltd duly commissioned a study into options for a high-speed route from a former British Rail civil engineer, Professor Andrew McNaughton. He examined no fewer than 32 pathways from London to Birmingham, on a technical and cost/benefit basis. From these he eliminated those running alongside existing road or rail pathways, such as the M1 or M40, as causing too much disruption to existing services. McNaughton, like all rail engineers, preferred open-country and out-of-town parkway stations. They offended fewer people – even if they served fewer. Of all the stations on the HS2 line, just three were planned for city centres, even though this might increase door-to-door journey times.

McNaughton settled on a 119-mile line, which would travel from Euston through an extensive former rail interchange at Old Oak Common in Acton, west London, and then north under the escarpment of the Chilterns to Birmingham’s derelict terminus at Curzon Street. The decision to “future-proof” the line to run at 400kmph was a case of engineering perfectionism. Such speed required a straighter line, meaning it was less able to avoid sensitive areas, and the additional speed added greatly to carbon consumption. High speed is anything but green.

Adonis published his white paper in March 2010, just two months before the election. It was a phenomenal achievement. He announced that the railway to Manchester, Birmingham and Leeds would cost £30bn for 335 miles of track, “with a substantial risk factor built in”. It received a warm reception in the House of Lords, though one peer commented acerbically that Adonis’s predecessor, Ruth Kelly, had just two years earlier called such a project “opportunistic, economically illiterate and hugely damaging to Britain’s national interests”.

Villiers responded that the Tories were “not prepared to blindly accept the route” proposed in the white paper – and excoriated the proposed line to Acton, and the construction of a new station at Old Oak Common, as plainly insufficient to connect the line to Heathrow. But she still proposed that the Tories were even more committed than Labour, and planned to “go further and faster” in pursuit of a “high-speed revolution.”

Adonis had achieved his primary purpose. A white paper was before parliament, a route was proposed and the Tories were at least half aboard. He had begun to shift the debate on HS2 from a question of whether to one of where.

In May 2010, Labour was out of office,and the transport portfolio passed not to Villiers but to a newcomer, Philip Hammond, who had to familiarise himself afresh with the subject. Meanwhile, focus turned to the Treasury as it grappled with recession and the impact of austerity on all public spending proposals. Soon after he became chancellor, George Osborne’s officials presented him with a list of Labour projects that were candidates for possible cuts. One was London’s Crossrail, a project that was then forecast to cost some £15bn and was almost as controversial as HS2. It was saved by Osborne’s soft spot for the City of London, for which Crossrail seemed virtually a private commuter line.

George Osborne in Crewe, on the proposed HS2 route. Photograph: Joe Giddens/PA

As for HS2, Cameron and his colleagues had publicly supported it. Osborne, like Adonis, had seen Japan’s bullet train and he had a weakness for megaprojects, which he viewed as a talisman of a virile, manufacturing-oriented Toryism. His staff found it hard to keep him out of a high-visibility jacket. Osborne declined to kill the project. Instead, he became the third member of the triumvirate – after Steer and Adonis – who have dragged HS2 towards fruition.

Steer now mobilised a wider constituency, he said, “of university academics, manufacturers, train operators, consultants”. Above all, he embraced the contractors who were bound to have an interest in so lucrative a project.

Osborne had seen Japan's bullet train and had a weakness for megaprojects which he saw as a talisman of a virile Toryism

In October 2010, the new government announced some of the deepest cuts in the history of public spending. The transport budget was to be cut by 15% in total. Yet Osborne specifically declared that HS2 was safe. The message was clear: there was no other gravy train. Anyone who wanted a share of transport spending had better sign up to HS2.

Just as the lobbyists for the project found new vigour, so did those opposed. The publication of the proposed route galvanised an entirely new constituency: those whose homes and lives would be upheaved by it. Numerous local protests cohered into Stop HS2, which was to keep HS2 Ltd under a withering fire of criticism. It liaised with the 18 local councils alongthe line of route, who set up 51M, a lobby named after the cost of HS2 in millions of pounds to each constituency in the UK.

As opposition mounted, the coalition government began to shift its case for HS2. Rather than the glory of speed, which would save business travellers a few minutes on trips into London, the argument for HS2 now invoked the more mundane issue of capacity – the need for more trains to carry passengers to and from the north. (Many people had pointed out that there was little point in advertising the “business time saved” by speed, when many business travellers said they could work rather well on a train.) “It was a mistake to go on about speed,” Steer now says. “HS2 was always really about capacity.”

But the need for additional capacity on the HS2 route was not entirely obvious. Published data appeared to show that Euston was the least-pressured London long-distance station: using only 60% of capacity in the morning peak, while trains at Paddington and Waterloo were over 100%.

There was no other gravy train. Anyone who wanted a share of transport spending had better sign up to HS2

Stephen Glaister, an Imperial College transport economist who was initially on one of HS2’s panels, became increasingly cynical about HS2’s use of figures. “HS2 was investigated against standard benefit-cost analysis for roads and other public projects,” Glaister told me. “When the economic appraisal didn’t wash, other arguments about wider social benefits started to be used, such as the north-south divide. When that didn’t stack up, they started talking about capacity. When even that didn’t give the right answer, the project became politically totemic.”

By 2012, the project had indeed attained such status. In September, when Cameron appointed Patrick McLoughlin as transport secretary, he told him HS2 was his priority. But while McLoughlin was to prove an ardent champion of high-speed rail, he became ever more beleaguered.

For all Osborne’s enthusiasm, some Treasury officials clearly saw the project as a ministerial ego trip. By 2013, Treasury officials suggested to the Financial Times that what had been a £30bn project, and then a £42bn project, was now starting to look more like a £72bn project. Other stories appeared suggesting that the cost could rise to as much as £80bn by the time construction started. The Major Projects Authority, which oversaw complex government projects, consistently gave the railway the rating “Amber/Red” – meaning a “high risk” of not delivering value for money.

In 2013, the National Audit Office issued a devastating charge, taken up by the commons Treasury select committee, that officials were using “fragile numbers, out-of-date data and assumptions that do not reflect real life”. The committee spoke of “serious shortcomings” in HS2’s cost-benefit analysis.

Similar doubts began to emerge over the most abstract justification for the project – that it would help mend the north-south divide. Studies of France’s TGV by an HS2 adviser, Roger Vickerman of Kent University, showed most benefits from new transport links went to the economically stronger end of the chain. This meant HS2 would merely make London even more magnetic an economic attractor.

In 2014, both Alistair Darling and John Prescott broke cover to express their opposition to the project. Darling warned that such “political visions can easily become nightmares”. Labour’s Lord Mandelson, who had previously supported the project, said HS2 was “an expensive mistake”. The Institute of Directors called it a “grand folly”. The Institute for Economic Affairs predicted a cost of £80bn and said the line “defies economic logic”. Even the Engineering Employers Federation demanded the money be switched to roads. The former chairman of Eurostar, Adam Mills, wrote an excoriating letter to the Times, calling HS2’s economics “away with the fairies”. He said the money should be spent “on traditional rail enhancements given the short distances between UK cities”.

Faced with this blizzard of opposition, Osborne appeared to weaken. On 1 January 2014, he moved his biggest available gun, Sir David Higgins, to the project. Higgins is an Australian civil engineer credited with bringing the Olympics to successful conclusion and then to getting to grips with Network Rail’s costs. He was charged with getting HS2 Ltd’s budget under control. The project was heading towards spending a billion pounds of public money before laying a yard of track.

Meanwhile Steer’s lobby plunged ahead. In 2014, they seized on Osborne’s declaration of a “northern powerhouse” to promote One North, a plan for a £15bn network, dubbed HS3, between Lancashire and Yorkshire. This was welcomed by the ever amenable Osborne as “affordable”, though its cost per mile was higher even than HS2. This inevitably led some northerners to wonder if HS3 might not be more in their interest. Osborne’s most loyal supporter, Manchester City council’s boss, Sir Howard Bernstein, admitted to me earlier this year that, if pushed to the wall, he would give HS3 his priority.

Meanwhile, in March this year, when the HS2 bill passed the Commons, Steer was euphoric. “It was not on the radar in 2006. Now it has MPs voting 10 to one in favour,” he said. His was undeniable one of the great coups in lobbying history.

There remained one obstacle to HS2 that no lobbying, no voting and no amount of public money could overcome. When looking at the options for possible routes, McNaughton had rejected Villiers’ original intention to bring the line into St Pancras – where it would meet HS1 coming from the Channel tunnel. He had opted for Euston. For railwaymen, Euston was always the network’s premier terminus. In 1838, it had been Britain’s first inter-city station. It was the closest “dispersal point” for passengers to central London and, as the existing terminus for trains from Birmingham and Manchester, it was the natural home for HS2.

That was all Euston had in its favour. In every other respect, it was unsuitable. It lies at the foot of a constricted incline from a tunnel through Primrose Hill, which leaves little room for new tracks or for handling longer high-speed trains. As the head of HS2 Ltd, David Rowlands had said back in 2010 that HS2 would need 10 platforms – but there was no room for these without curtailing Euston’s existing capacity, which would undermine the principal justification for HS2. The work would also take seven to 10 years and any loss, temporary or permanent, to existing services would lead Virgin and other Euston operators to demand billions in compensation.

More seriously, Euston has poor east-west connectivity, as it is not on the tube’s Circle, District, Metropolitan or Central lines. Nor did anyone think to put it on the new Crossrail link from Paddington to the City. This meant that HS2 would enter London half a mile adrift of HS1 and trains to mainland Europe. North-country passengers wishing to transfer to the Eurostar would have either to take one stop on the Northern line tube, or trundle their bags down busy Euston Road.

At this point, those who sing HS2’s praises go strangely quiet. Since 2015, it has been ever clearer that all three “parents” of the project have become sceptical of the Euston decision. Adonis himself is openly regretful. “HS2 should stop at Old Oak Common,” he told me, “interchanging with Crossrail there. We should leave open the question of going further into London.” As head of the Cameron’s national infrastructure commission, Adonis makes many speeches on these subjects. He nowadays lauds HS3, and lauds Old Oak Common as London’s greatest development opportunity. I have yet to hear him laud Euston. That station, he says, “is the poison at the heart of HS2. I bitterly regret not stopping it before I left office”.

Like Adonis, Steer sees trouble ahead. While he believes that Old Oak Common would be “a hard sell”, he finds it difficult to see how Euston can accommodate both HS2 and the existing customers. His alternative is to cut four existing platforms at Euston and bring their services to stop at Old Oak Common. “By taking half the trains and half the passengers from Euston, we could use that capacity for HS2,” he said. Such a proposal is unlikely to find favour with Virgin, let alone with Euston’s commuters. There would be a riot.

As for Osborne, he can only be worried. In the clearest possible sign of trouble, the cabinet secretary, Sir Jeremy Heywood, was ordered to investigate the project. In March 2016, the Treasury was reported to be looking at cost-cutting options. One option was to halt the Manchester arm of HS2’s pathway at Crewe, 36 miles south of Manchester, and for the trains to proceed on existing track. Another was indeed to abandon Euston for Adonis’s Old Oak Common option. The new London mayor, Sadiq Khan has also demanded “another look” at Euston – he told me last month that he thought the railway should stop at Old Oak Common.

The forces now ranged against completing HS2 as planned are becoming formidable. If the other mooted cuts are made, Britain’s first long high-speed route could start at Acton and end at Crewe. This would verge on white elephant status.

HS2 was always a project born of political vanity. Like several other unstoppable megaprojects, it was not rooted in commercial reality or value for money – and it has therefore not been halted by accusations that it is not needed and not worth the cost. It may have been a noble idea, but one that could only fly with huge amounts of public money, and that now is in short supply. Osborne joked recently that his favourite diet was “eating my own words”. He may have a feast ahead of him.

Main image: Sara Ramsbottom

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